The present invention generally relates to a process for hydraulic transport of bulk material from a receiving site to a remote location.
The dissertation, entitled "Hydraulische Forderung von Eis zum Kuhlen von Bergwerken", and issued by the Technical University of Hannover, 1991, discloses a test plant for hydraulically conveying a mixture of ice and water. The test plant includes essentially a closed ring-shaped pipeline which is supplied from a vacuum-ice machine with a dispersion of ice and water, whereby the content of ice is relatively low. By means of a centrifugal pump, the ice content is increased by pumping the dispersion at low flow rate in the circular path, while a volume flow of water is withdrawn from the pipeline via an integrated screen pipe whereby the withdrawn volume flow of water is equal to the volume flow of the ice/water dispersion fed from the vacuum-ice machine, and is returned to the vacuum-ice machine. When the desired ice content is reached, the pump output is increased until the desired flow velocity for the test is realized. The increase of the ice content of the dispersion is however rather limited because the output of a centrifugal pump progressively deteriorates as the ice content, i.e. solids content, rises. Thus, this conventional test plant is unsuitable for efficient and economical hydraulic transport of bulk material from a receiving site to a remote location.
European Pat. No. 0,194,498 B1 describes a process and apparatus for clocked hydraulic transport of a turbid medium. The apparatus includes a reservoir for turbid medium with associated feed pump, a storage tank for liquid with associated fluid pump, a plurality of parallel metering chambers and a conveying pipeline. These components of the apparatus are connected to one another by conduits which can be shut off individually. The feed pump draws turbid medium from the reservoir to alternately fill the metering chambers in opposition to the conveying direction with turbid medium, whereby part of the liquid components of the turbid medium is withdrawn by suction by a jet pump via a compression chamber, which is associated to the metering chamber and provided with a screen, and conducted to the storage tank. In this manner, the solids concentration can be increased. By changing the position of the shut-off valves in the conduits, the turbid medium content is subsequently pressed from the metering chamber in conveying direction into the conveying pipeline by means of a liquid stream withdrawn by the fluid pump from the storage tank. During subsequent renewed filling of the metering chamber with turbid medium in opposite direction, the liquid is forced out of the metering chamber back into the storage tank. In this process, only solids-free liquid is conducted through the fluid pump that generates the conveying pressure. Moreover, the feed pump for turbid medium generates only a low pressure and conveys the turbid medium with a solids content which is significantly smaller than the solids content of the turbid medium in the conveying pipeline. The implementation of this process is disadvantageous because of the need for a rather complicated apparatus as well as the clocked introduction of the medium stream into the conveying pipeline.